Men cannot change their nature. People cannot change their nature. People can evolve, rebirth and grow, and a person's nature usually remains the same. In fact, spirits don't change. A person's spirit, is usually who they truly are. A man cannot change his nature. He can modify it. He can change his behavior, or actions, but he cannot change his nature. In other words, he can't change his biological make-up. What's his nature? Is he nice? spiritual? thoughtful? honest? goofy? fun? serious? mean spirited? is he a cheater? Is he self centered? Is he a humanitarian? Is he caring? Whatever his nature is, don't expect anything much different from his actions. You're nature influences your actions. If his actions are different from his nature, it will only last for a short while. Why? because when you do what is opposite from what you feel, a psychological tension occurs, which creates an incongruence. People aim to be consistent within their actions.
His spirit is his nature and his nature is who he truly is. You will know a man by his fruit that he bares.
Things are so much clearer when you view him as a person, and not as a man.